: Letters or symbols painted on aircraft tails identified the group and its division. For instance, a "Square J" identified the 390th Bomb Group.
: Many units developed famous nicknames, such as the "Bloody Hundredth" (100th BG) or the "Jolly Rogers" (90th BG). Key Resources & Research Tools bomb group
: A group was usually made up of four squadrons. For example, the 397th Bomb Group included the 596th, 597th, 598th, and 599th squadrons. : Letters or symbols painted on aircraft tails
For those researching a specific unit or relative, several foundations and archives provide detailed guides: 100th BG Reference Guide bomb group